[icegreentea2]

787 was announced in 2003, and the first shipment was in 2012. Obviously we have no idea what the extent of work was prior to the announcement.

A220 was officially launched in 2008 (with like 3-5 more years of some degree of development prior to that) and first delivery was in 2016.

A350 was officially launched in 2004 and first delivery was 2014.

Expecting 8-12 years would be reasonable.